KR101193339B1 - Secondary cell system - Google Patents

Abstract

The secondary battery system which can detect the state (state of a secondary battery, abnormality of a secondary battery system, etc.) of a secondary battery system with high precision is provided. The secondary battery system 6 has a battery voltage V of the secondary battery 100 with respect to the change amount dQ of the electricity storage amount Q when the electricity storage amount Q of the secondary battery 100 is changed. And dV / dQ calculating means for calculating a value of dV / dQ, which is a ratio of the change amount dV of (). The secondary battery system 6 detects the state of the secondary battery system 6 using the value of dV / dQ.

Description

Secondary Battery System {SECONDARY CELL SYSTEM}

The present invention relates to a secondary battery system.

Various things are proposed as a secondary battery system which detects the state of a secondary battery. For example, in Patent Documents 1 to 4, the state of charge (power storage amount or SOC) of the secondary battery is detected based on the battery voltage of the secondary battery. Among these, Patent Document 4 also detects the deterioration state of the secondary battery based on the SOC (State Of Charge) calculated based on the battery voltage and the battery temperature detected by the temperature detecting means.

Patent Document 1: Japanese Unexamined Patent Publication No. 2007-292778 Patent Document 2: Japanese Patent Application Laid-Open No. 11-346444 Patent Document 3: Japanese Patent Application Laid-Open No. 7-294611 Patent Document 4: Japanese Unexamined Patent Publication No. 2001-33532 Patent Document 5: Japanese Unexamined Patent Publication No. 2003-36889

However, in the methods proposed in Patent Documents 1 to 4, when the amount of change in battery voltage accompanied by the change in power storage amount is small, there is a fear that the state of charge (power storage amount or SOC) of the secondary battery can not be properly detected. have. Moreover, in such a case, there exists a possibility that the deterioration state of a secondary battery may not be detected suitably by the method proposed by patent document 4, too.

Moreover, the lithium ion secondary battery which changes in output density is small recently and can obtain stable output characteristics is proposed (for example, refer patent document 5). The secondary battery disclosed by patent document 5 is a battery which accompanies the change of electrical storage quantity over 50% or more of capacity | capacitance ranges (specifically, SOC 25%-80% of capacity range) of the whole theoretical electric capacity. The change in voltage is very small. Especially for such a secondary battery, there was a possibility that the state (charge state or deteriorated state) of the secondary battery could not be detected.

This invention is made | formed in view of such a phenomenon, and an object is to provide the secondary battery system which can detect the state (state of a secondary battery, abnormality of a secondary battery system, etc.) of a secondary battery system with high precision. It is done.

One embodiment of the present invention is a secondary battery system including a secondary battery, wherein the secondary battery includes an electrode body having a first electrode plate, a second electrode plate, and a separator. And a first active material accompanying a phase change by charging and discharging, wherein the second electrode plate includes a second active material which performs charge / discharge of a two-phase coexistence type, and the secondary battery system includes the secondary The amount of change (dV) of the battery voltage V of the secondary battery to the amount of change dQ of the electrical storage amount Q when the electrical storage amount Q of the secondary battery is changed at the time of charging or discharging the battery. And a dV / dQ calculating means for calculating a value of dV / dQ, which is a ratio of h), and a feature point appearing on a Q-dV / dQ curve indicating a relationship between the value of the electric storage amount Q and the value of the dV / dQ. Or 2 using the feature points appearing on the V-dV / dQ curve representing the relationship between the value of the battery voltage V and the value of dV / dQ. It is a secondary battery system which detects the state of a secondary battery system.

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In a secondary battery having an active material with a phase change by charging and discharging, distinct feature points (maximum points, local points, etc.) appear on the Q-dV / dQ curve and the V-dV / dQ curve. In addition, "an active material with a phase change by charging / discharging" means an active material which changes a crystal structure in the middle of charging / discharging, and can illustrate a carbon material. Examples of the carbon material include natural graphite materials, artificial graphite materials (such as mesocarbon microbeads), egg-graphitized carbon materials, and the like.
The secondary battery of the system described above includes a first active material in which the first electrode plate carries a phase change by charge and discharge, and the second electrode plate comprises a second active material in which charge and discharge of a two-phase coexistence type are performed. have. In such a secondary battery, clear feature points (maximum point, minimum point, etc.) appear on the Q-dV / dQ curve and the V-dV / dQ curve. For this reason, in the above-mentioned secondary battery system, the state of a secondary battery can be detected with high precision using this clear characteristic point.
In addition, the "second active material which performs charge / discharge of a two-phase coexistence type" means the active material which charge-discharge reaction is performed in the state which two crystal | crystallization which differs in crystal structure coexists, for example, LiFe _{(1- X)} M _X PO ₄ (M is at least one of Mn, Cr, Co, Cu, Ni, V, Mo, Ti, Zn, Al, Ga, Mg, B, Nb, 0≤X≤0.5) , LiMn _(1-X) M _X PO ₄ (M is at least one of Cr, Co, Cu, Ni, V, Mo, Ti, Zn, Al, Ga, Mg, B, Nb, and 0≤X≤ The compound of the olivine structure shown by 0.5) is mentioned.
In the above-described secondary battery system, the state of the secondary battery system is detected using the value of dV / dQ. In detail, the state of a secondary battery system is detected using the characteristic point shown on a Q-dV / dQ curve, or the characteristic point shown on a V-dV / dQ curve. Thereby, the state of a secondary battery system can be detected with high precision.

Moreover, as a state of a detectable secondary battery system, the state of a secondary battery, the abnormality of a secondary battery system, etc. are mentioned, for example. As a state of a secondary battery, the state of charge (capacity and SOC) and deterioration state of a secondary battery can be illustrated. Among these, as a deteriorated state of a secondary battery, the fall of a battery capacity (full charge capacity), the raise of internal resistance, etc. are mentioned, for example. Moreover, as an abnormality of a secondary battery system, the internal short circuit of a secondary battery, the connection defect of a secondary battery, etc. can be illustrated.

Specifically, even if the amount of change in battery voltage V accompanied by the change in power storage amount Q is small, the amount of change in the value of dV / dQ accompanying the change in power storage amount Q tends to increase. Therefore, the state detection of the secondary battery system is performed based on the value of dV / dQ (in detail, using a feature point appearing on a Q? DV / dQ curve or a feature point appearing on a V? DV / dQ curve). By doing so, the state of the secondary battery system can be detected with high accuracy. For example, based on the value of dV / dQ (in detail, using a feature point appearing on a Q? DV / dQ curve or a feature point appearing on a V? DV / dQ curve), the state of the secondary battery is detected. By doing so, the state (charge state or deteriorated state) of the secondary battery can be detected with high accuracy. Also, based on the value of dV / dQ (in detail, using a feature point appearing on a Q? DV / dQ curve or a feature point appearing on a V? DV / dQ curve), an abnormality of the secondary battery system ( Internal short circuit of the secondary battery or poor connection of the secondary battery can be detected.

Moreover, it is said secondary battery system, The said secondary battery is a characteristic point on the Q-dV / dQ curve which shows the relationship of the value of the said electrical storage quantity Q with respect to the said secondary battery, and the value of dV / dQ. It is preferable to set it as the secondary battery system which has a.

The characteristic points on the Q-dV / dQ curve are maximum points, minimum points, and inflection points. Since the feature point on the Q-dV / dQ curve is very easy to detect, the state of the secondary battery system can be detected more accurately by using this feature point.

For example, in the secondary battery system which estimates the electrical storage amount of a secondary battery, a deviation may arise between an actual electrical storage amount and an estimated electrical storage amount by some cause. Therefore, in the system, the value of the electrical storage amount Q (which is referred to as the characteristic reference value QK) at the characteristic point on the Q-dV / dQ curve is stored in the system in advance, and the characteristic reference value QK and the secondary battery system The power storage amount Q (feature estimation value QS) at the estimated feature point is compared. By calculating the difference value between the feature reference value QK and the feature estimate value QS, the estimated deviation of the secondary battery system can be grasped. Thus, for example, by accumulating the estimated estimated power storage amount with the difference value, the power storage amount Q with high accuracy can be detected. In addition, the fall of battery capacity (full charge capacity) can be detected with high precision by using the characteristic point on a Q-dV / dQ curve as mentioned later.

Moreover, in any one of said secondary battery systems, said secondary battery is on the V-dV / dQ curve which shows the relationship of the value of the said battery voltage (V) and the value of said dV / dQ regarding the said secondary battery. It is preferable to set it as the secondary battery system which has a characteristic point in.

The characteristic points on the V-dV / dQ curve are maximum points, minimum points, and inflection points. Since the feature point on the V-dV / dQ curve is very easy to detect, the state of the secondary battery can be detected with high accuracy by using this feature point.

Specifically, for example, as described later, an increase in the internal resistance of the secondary battery can be detected with high accuracy by using a feature point on the V-dV / dQ curve.

In addition, the secondary battery system is the above-described secondary battery system, the secondary battery system, based on the value of the dV / dQ, whether the secondary battery has reached a state corresponding to the feature point on the Q-dV / dQ curve and At least one of whether or not the secondary battery has reached a state corresponding to a feature point on the V-dV / dQ curve is determined, and the amount of power storage Q at the feature point on the Q-dV / dQ curve is determined. A plurality of feature points present on the V-dV / dQ curve or the difference value of the power storage amount Q at two specific feature points selected from a value, a plurality of feature points present on the Q-dV / dQ curve. What is necessary is just to set it as the secondary battery system which detects the state of the said secondary battery system based on the difference value of the said battery voltage V in the specific 2 characteristic points selected from the above.

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Further, any one of a secondary battery system, and the second active _{material, LiFe (1- X) M X} PO 4 (M is, Mn, Cr, Co, Cu, Ni, V, Mo, Ti, Zn, At least one of Al, Ga, Mg, B, and Nb, and 0 ≦ X ≦ 0.5), and the first active material may be a secondary battery system made of a carbon material.

In a secondary battery using a carbon material as the first active material and using LiFe _(1-X) M _X PO ₄ as the second active material, a battery voltage of about 3.4 V and corresponding to about 80% of the theoretical electric capacity Can charge and discharge. Therefore, in the above-described secondary battery system, the battery can be charged and discharged at a relatively high battery voltage of about 3.4V over a capacity range of about 80% of the theoretical electric capacity, so that a high output can be obtained stably.

By the way, in the case of a secondary battery having a small variation in battery voltage over a wide capacity range of about 80% of the theoretical capacitance, the method of detecting the state (charge state or deterioration state) of the secondary battery based on the battery voltage There is a possibility that the state of the secondary battery cannot be properly detected. However, in the above-described secondary battery system, as described above, since the state of the secondary battery is detected based on the value of dV / dQ, the state of the secondary battery can be detected with high accuracy.

In addition, according to any one of the above secondary battery systems, the secondary battery is based on the electric storage amount estimating means for estimating the electric storage amount Q of the secondary battery and the value of the dV / dQ. determining means for determining whether a state corresponding to the feature point indicated on the dV / dQ curve has been reached; and power storage amount correcting means for correcting the estimated power storage amount Q; The electrical storage amount when the secondary battery has reached the state corresponding to the characteristic point by the determining means from the characteristic reference value which is the value of the electrical storage amount Q at the characteristic point stored in the secondary battery system; What is necessary is just to set it as the secondary battery system which correct | amends the estimated electrical storage quantity Q by the difference value which subtracted the characteristic estimation value which is the value of the electrical storage quantity Q of the said secondary battery estimated by the estimation means.

In the secondary battery system for estimating the electrical storage amount Q of the secondary battery, a deviation may occur between the actual electrical storage amount and the estimated electrical storage amount due to something.

In contrast, in the above-described secondary battery system, the estimated power storage amount Q is corrected using the value of dV / dQ. Specifically, for example, the system stores the value of the electrical storage amount Q (which is referred to as the characteristic reference value QK) at the characteristic point on the Q-dV / dQ curve described above in advance in the system. The power storage amount Q (which is referred to as the feature estimation value QS) at the estimated feature point in the secondary battery system is compared. And by calculating the difference value of the characteristic reference value QK and the characteristic estimation value QS, the estimated shift | offset | difference of a secondary battery system can be detected. Therefore, by accumulating the estimated electrical storage amount estimated by the electrical storage amount estimation means by the said difference value, high electrical storage quantity Q can be detected.

In this manner, in the above-described secondary battery system, the electrical storage amount Q can be detected with high accuracy.

Further, in any one of the above secondary battery systems, the secondary battery is placed on the Q-dV / dQ curve based on deterioration detection means for detecting deterioration of the secondary battery and the value of dV / dQ. Determination means for judging at least one of whether a state corresponding to a feature point that appears and whether or not the secondary battery has reached a state corresponding to a feature point that appears on the V-dV / dQ curve are provided; In the deterioration detection means, the difference value of the power storage amount Q at two specific feature points selected from a plurality of feature points present on the Q-dV / dQ curve determined by the determination means is set in advance. The former at two specific points selected from a plurality of feature points present on the V-dV / dQ curve when smaller than a reference difference value or determined by the judging means; The difference value of the voltage (V), may be a secondary battery system that determines that a larger than the reference difference value if a previously set, the secondary battery is deteriorated.

In the above-mentioned secondary battery system, deterioration of a secondary battery is detected using the value of dV / dQ. Moreover, as deterioration of a secondary battery, the fall of a battery capacity (full charge capacity), an increase of internal resistance, etc. are mentioned, for example.

Specifically, the inventors of the present invention show that as the battery capacity (full charge capacity) of the secondary battery is lowered, the storage capacity (Q) corresponding to each characteristic point (maximum point, minimum point, etc.) in the Q-dV / dQ curve described above. The characteristic that the difference value (DELTA) Q of () becomes small was discovered. By using this characteristic, the fall of a battery capacity (full charge capacity) can be detected based on difference value (DELTA) Q, for example.

In addition, the present inventors, as the internal resistance of the secondary battery rises, in the above-described V-dV / dQ curve, the difference value (ΔV) of the battery voltage (V) corresponding to each feature point (maximum point, minimum point, etc.) Found a growing characteristic. Using this characteristic, an increase in the internal resistance of the secondary battery can be detected based on, for example, the difference value ΔV.

Moreover, it is said secondary battery system and based on the value of said dV / dQ, the said secondary battery system has reached | attained the state corresponding to the characteristic point shown on the said Q-dV / dQ curve by the said secondary battery. And deciding means for judging whether the deterioration detecting means includes a lowering capacity detecting means for detecting a lowering of the battery capacity of the secondary battery, and the lowering capacity detecting means is previously provided to the secondary battery system. The reference difference value which is a difference value of the power storage amount Q at the two feature points on the Q? DV / dQ curve stored, the reference difference value for the secondary battery in an initial state, and the When the measured difference value is smaller than the reference difference value in contrast to the measured difference value that is the difference value of the power storage amount Q at the two feature points on the Q-dV / dQ curve judged by the determination means. On, May be a secondary battery system determines that the battery capacity of the secondary battery group is lowered.

As described above, as the battery capacity (full charge capacity) of the secondary battery is lowered, the difference value of the electric storage amount Q corresponding to each characteristic point (maximum point, local minimum point, etc.) in the Q-dV / dQ curve. (ΔQ) decreases. By using this characteristic, the fall of a battery capacity (full charge capacity) can be detected, for example based on the difference value (DELTA Q) in a Q-dV / dQ curve.

Specifically, for example, in a Q-dV / dQ curve acquired for a secondary battery before deterioration (initial state), the difference value between the storage value corresponding to a certain feature point A and the storage value corresponding to another feature point C (ΔQ) (referred to as the reference difference value ΔQK) is calculated, and the reference difference value ΔQK is stored in the system. In the secondary battery system, a difference value ΔQ (a measured difference value ΔQS) is calculated every predetermined time, and the measured difference value ΔQS and the reference difference value ΔQK are compared.

When the measured difference DELTA QS is smaller than the reference difference DELTA QK, it can be determined that the capacity decrease of the secondary battery has occurred. Moreover, the degree of the capacity | capacitance fall of a secondary battery can also be estimated by the comparison of a reference difference value (DELTA QK) and the measured difference value (DELTA QS). In addition, it is also possible to correct the power storage amount Q estimated by the system based on the estimated degree of capacity drop.

The secondary battery system may be any one of the above-described secondary battery systems, and the secondary battery system may be in a state corresponding to a feature point in which the secondary battery appears on the V-dV / dQ curve based on the value of dV / dQ. Determination means for determining whether it has reached, wherein the deterioration detection means includes resistance increase detection means for detecting an increase in the internal resistance of the secondary battery, and the resistance rise detection means includes the secondary battery in advance. A reference difference value that is a difference value of the battery voltage V at the two feature points on the V-dV / dQ curve stored in the system, and the reference difference value for the secondary battery in an initial state; The measured difference value is larger than the reference difference value in contrast to the measured difference value that is the difference value of the battery voltage V at the two feature points on the V-dV / dQ curve determined by the determination means. In this case, the secondary battery system may determine that the internal resistance of the secondary battery is rising.

As described above, as the internal resistance of the secondary battery increases, the difference value ΔV of the battery voltage V corresponding to each characteristic point (maximum point, local minimum point, etc.) increases in the V-dV / dQ curve. Goes. By using this characteristic, the increase of the internal resistance of a secondary battery can be detected based on the difference value (DELTA) V in a V-dV / dQ curve, for example.

Specifically, for example, in the V-dV / dQ curve acquired for the secondary battery before deterioration (initial state), the difference value between the battery voltage corresponding to a certain feature point D and the battery voltage corresponding to another feature point E (ΔV) (referred to as the reference difference value ΔVK) is calculated, and the reference difference value ΔVK is stored in the system. In the secondary battery system, the difference value ΔV (measured as the measured difference value ΔVS) is calculated every predetermined time, and the measured difference value ΔVS is compared with the reference difference value ΔVK.

When the measured difference value ΔVS is larger than the reference difference value ΔVK, it can be determined that the internal resistance of the secondary battery is rising. Further, the degree of increase in the internal resistance can also be estimated by comparing the reference difference value? VK and the measured difference value? VS. It is also possible to correct the power storage amount Q estimated by the system based on the estimated degree of increase in the internal resistance.

The secondary battery is any one of the above secondary battery systems, and on the basis of the Q-dV / dQ curve, the secondary battery has an abnormality detecting means for detecting an abnormality of the secondary battery system and the value of dV / dQ. Determination means for judging at least one of whether a state corresponding to the feature point shown in Fig. 2 has been reached and whether the secondary battery has reached a state corresponding to the feature point shown on the V-dV / dQ curve; In the abnormality detecting means, a difference value of the power storage amount Q at two specific feature points selected from a plurality of feature points present on the Q-dV / dQ curve determined by the determining means is set in advance. Selected from a plurality of feature points present on the V-dV / dQ curve when smaller than a reference difference value and smaller than a predetermined threshold value or determined by the determination means; The secondary battery system which judges that the said secondary battery system is abnormal, when the difference value of the said battery voltage V in two characteristic points is larger than predetermined reference difference value and larger than predetermined threshold value. You can do it.

In the above-mentioned secondary battery system, abnormality of a secondary battery system is detected using the value of dV / dQ. As an abnormality of the detectable secondary battery system, for example, occurrence of an internal short circuit of a secondary battery, connection failure of a secondary battery (connection failure of a connection terminal of a cable connected to an external terminal of a secondary battery, or two Poor connection of the connecting member for connecting the terminals of the secondary battery).

Specifically, the secondary battery in which the internal short circuit has occurred is characterized in that each feature point on the Q-dV / dQ curve described above is compared with the secondary battery (including the reduced capacity secondary battery) in which no short circuit has occurred. The difference value ΔQ of the electrical storage amount Q corresponding to the maximum point, the minimum point, etc.) becomes extremely small. By using this feature, for example, when the difference value ΔQ is lower than a predetermined threshold value (eg, 60% of the reference difference value ΔQK), an internal short circuit occurs in the secondary battery. You can judge.

In addition, when the connection failure of the secondary battery is generated, compared with the case where there is no connection failure, the battery voltage V corresponding to each characteristic point (maximum point, local point, etc.) on the above-described V-dV / dQ curve is The difference value ΔV becomes extremely large. Using this feature, for example, when the difference value ΔV exceeds a predetermined threshold value (for example, three times the reference difference value ΔVK), it can be determined that a connection failure has occurred. .

Moreover, it is said secondary battery system and based on the value of said dV / dQ, the said secondary battery system has reached | attained the state corresponding to the characteristic point shown on the said Q-dV / dQ curve by the said secondary battery. Determination means for judging whether or not, the abnormality detection means includes non-short detection means for detecting the short-circuit of the secondary battery, and the non-short detection means is stored in the secondary battery system in advance. The reference difference value which is the difference value of the power storage amount Q in the two feature points on the Q-dV / dQ curve, and the reference difference value for the secondary battery in an initial state, and the determination means. The measured difference value is smaller than the reference difference value and is smaller than the reference difference value in contrast to the measured difference value that is the difference value of the power storage amount Q at the two feature points on the Q-dV / dQ curve determined by. Than the threshold of Even if it is small, what is necessary is just to set it as the secondary battery system which judges that the short circuit has generate | occur | produced in the said secondary battery.

As described above, the secondary battery in which the internal short circuit has occurred has a characteristic point (maximum point) on the Q-dV / dQ curve as compared with the secondary battery in which no short circuit has occurred (including the reduced secondary battery). (Minimum point, etc.), the difference value ΔQ of the electrical storage amount Q is extremely small. Using this feature, the internal short circuit can be detected based on the difference value ΔQ, for example.

Specifically, for example, in a Q-dV / dQ curve obtained for a secondary battery in which no short-circuit has not occurred in advance (in an initial state), the amount of power storage corresponding to a certain feature point A corresponds to a different feature point C. The difference value ΔQ (set as the reference difference value ΔQK) of the power storage amount is calculated, and the reference difference value ΔQK is stored in the system. In the secondary battery system, a difference value ΔQ (a measured difference value ΔQS) is calculated every predetermined time, and the measured difference value ΔQS and the reference difference value ΔQK are compared. When the measured difference value ΔQS is lower than a predetermined threshold value (for example, a value corresponding to 60% of the reference difference value ΔQK), it can be determined that an internal short circuit has occurred in the secondary battery. . In this case, a signal indicating that the secondary battery is abnormal may be output to prompt replacement of the secondary battery.

The secondary battery system may be any one of the above-described secondary battery systems, and the secondary battery system may be in a state corresponding to a feature point in which the secondary battery appears on the V-dV / dQ curve based on the value of dV / dQ. And determining means for determining whether or not it has arrived, wherein the abnormality detection means includes connection failure detection means for detecting connection failure of the secondary battery, and the connection failure detection means is previously provided to the secondary battery system. It is a reference difference value which is a difference value of the said battery voltage (V) in the said two characteristic points on the said V-dV / dQ curve stored, The said reference difference value about the said secondary battery of an initial state, and the said determination The measured difference value is larger than the reference difference value in contrast to the measured difference value that is the difference value of the battery voltage V at the two feature points on the V-dV / dQ curve determined by the means. If a larger than the predetermined threshold value, may be a secondary battery system determines that the connection failure of the secondary battery is generated.

As described above, when the connection failure of the secondary battery occurs, the battery voltage (V) corresponding to each characteristic point (maximum point, minimum point, etc.) of the above-described V-dV / dQ curve is higher than when the connection is normal. ), The difference value ΔV becomes extremely large. Using this feature, for example, when the difference value ΔV exceeds a predetermined threshold value, it can be determined that a connection failure has occurred.

Specifically, for example, in the V-dV / dQ curve obtained for the secondary battery in the initial state in the absence of a connection failure in advance, the battery voltage corresponding to a certain feature point D and the battery voltage corresponding to another feature point E are different. The difference value ΔV (which is referred to as the reference difference value ΔVK) is calculated, and the reference difference value ΔVK is stored in the system. In the secondary battery system, the difference value ΔV (measured as the measured difference value ΔVS) is calculated every predetermined time, and the measured difference value ΔVS is compared with the reference difference value ΔVK. When the measured difference value ΔVS exceeds a predetermined threshold value (for example, a value corresponding to three times the reference difference value ΔVK), it can be determined that a connection failure has occurred. In this case, a signal indicating that the connection is defective may be output to prompt confirmation of the connection.

1 is a schematic diagram of a hybrid vehicle according to a first embodiment.
2 is a schematic diagram of a secondary battery system according to a first embodiment.
3 is a cross-sectional view of a secondary battery according to the first embodiment.
4 is a sectional view of an electrode body according to the first embodiment.
FIG. 5 is a partially enlarged cross-sectional view of the electrode body according to the first embodiment, which corresponds to an enlarged view of portion B of FIG. 4.
6 is a diagram showing a potential curve vs. Li of a positive electrode active material.
7 is a diagram showing a potential curve vs. Li of a negative electrode active material.
8 is a charging characteristic diagram of a secondary battery.
9 is a diagram showing a Q-dV / dQ curve of a secondary battery.
10 is a flowchart showing the flow of state detection of the secondary battery according to the first embodiment.
11 is a schematic diagram of a secondary battery system according to a second embodiment.
It is a figure which compares the state detection precision of a 2nd Example and a 1st comparative example.
It is a figure which shows the Q-dV / dQ curve of the secondary battery with reduced capacity.
It is a figure which shows the Q-dV / dQ curve of the secondary battery of an initial state.
15 is a graph showing the relationship between the battery capacity (full charge capacity) and ΔQ.
16 is a schematic diagram of a secondary battery system according to a third embodiment.
17 is a main routine of state detection processing of the secondary battery according to the third embodiment.
18 is a subroutine of state detection processing of a secondary battery according to the third embodiment.
It is a figure which shows the V-dV / dQ curve of the secondary battery which the internal resistance rose.
20 is a diagram showing a V-dV / dQ curve of a secondary battery in an initial state.
21 is a graph showing the relationship between the internal resistance (mΩ) and ΔV.
22 is a schematic diagram of a secondary battery system according to a fourth embodiment.
23 is a main routine of state detection processing of the secondary battery according to the fourth embodiment.
24 is a subroutine of state detection processing of a secondary battery according to the fourth embodiment.
It is a figure explaining the connection of a positive electrode terminal and a cable.
It is a figure which shows the V-dV / dQ curve of a secondary battery.

(First embodiment)

Next, a first embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the hybrid vehicle 1 has a vehicle body 2, an engine 3, a front motor 4, a rear motor 5, a cable 7, and a secondary battery system 6. And a hybrid vehicle driven by the engine 3, the front motor 4, and the rear motor 5 in combination. Specifically, this hybrid vehicle 1 uses the secondary battery system 6 as a power source for driving the front motor 4 and the rear motor 5, and the engine 3 and the front motor ( 4) and the rear motor 5 are configured to travel.

Among these, the secondary battery system 6 according to the first embodiment is attached to the vehicle body 2 of the hybrid vehicle 1, and the front motor 4 and the rear motor 5 are connected by the cable 7. ) Is connected. As shown in FIG. 2, the secondary battery system 6 includes an assembled battery 10 in which a plurality of secondary batteries 100 (single cells) are electrically connected in series with each other, and a voltage detecting means 40. And a current detecting means 50 and a battery controller 30. The battery controller 30 has a ROM 31, a CPU 32, a RAM 33, and the like.

The current detection means 50 detects the current value I flowing through the secondary battery 100 constituting the assembled battery 10. In addition, the voltage detecting means 40 detects the battery voltage V (terminal voltage) with respect to each of the secondary batteries 100 constituting the assembled battery 10.

The battery controller 30 accumulates the current value I detected by the current detecting means 50 every predetermined time T, and calculates the amount of charged electricity or discharged electricity of the secondary battery 100, and calculates the calculated value. The electrical storage amount Q of the secondary battery 100 is estimated from the charged electricity amount or the discharge electricity amount. In addition, the battery controller 30 acquires the battery voltage V of each secondary battery 100 detected by the voltage detecting means 40 every predetermined time T in synchronization with the current integration.

The battery controller 30 further includes the battery voltage V of the secondary battery 100 with respect to the amount of change dQ of the electrical storage amount Q when the electrical storage amount Q of the secondary battery 100 is changed. The value of dV / dQ which is a ratio of the change amount dV of () is calculated. In other words, at the time of charging / discharging of the secondary battery 100, the battery voltage V of the secondary battery 100 is differentiated by the storage amount Q corresponding thereto to calculate the value of dV / dQ. . Specifically, at the time of charging / discharging of the secondary battery 100, the battery voltage V for each predetermined time T while acquiring the battery voltage V and the power storage amount Q for each predetermined time T. The amount of change dV and the amount of change dQ of power storage amount Q are calculated, and the value of dV / dQ for each predetermined time T is calculated based on these values.

In the ROM 31 of the battery controller 30, a Q-dV / dQ curve K indicating a relationship between the value of the storage value Q acquired in advance for the secondary battery 100 and the value of dV / dQ is shown. (Refer to FIG. 9). In addition, the value of the electrical storage amount Q at the characteristic point A (maximum point) on the Q-dV / dQ curve K (set as the characteristic reference value QKA) and the electrical storage amount at the characteristic point B (minimum point) ( The ROM 31 stores the value of Q) (set as the feature reference value QKB) and the value of the power storage amount Q (set as the feature reference value QKC) at the feature point C (maximum point).

In addition, the battery controller 30 draws a Q-dV / dQ curve in real time based on the value of dV / dQ calculated for each predetermined time T, and to the Q-dV / dQ curve and the ROM 31. Due to the contrast (pattern matching) of the stored Q-dV / dQ curve K (see FIG. 9), the secondary battery 100 has any of the feature points A, B, and C on the Q-dV / dQ curve. It is determined whether or not the state corresponding to the step S has reached.

For example, when it determines with having reached | attained the state corresponding to the characteristic point A, when the characteristic point A is reached, the electrical storage quantity Q of the secondary battery 100 estimated by the battery controller 30 (feature estimation value QSA). And the feature reference value QKA stored in the ROM 31. Specifically, the difference value QKA-QSA is calculated by subtracting the feature estimated value QSA from the feature reference value QKA.

When the absolute value of this difference value QKA-QSA is larger than 0.1 Ah, for example, it can be considered not as a simple measurement error but as the estimated misalignment of the electrical storage amount in the secondary battery system 6. Therefore, in the battery controller 30 of the first embodiment, when the absolute value | QKA-QSA | of the difference value is larger than 0.1 Ah, the battery controller 30 estimates the difference value QKA-QSA. The power storage amount Q of the secondary battery 100 thus obtained is corrected. Specifically, the difference value QKA-QSA is added to the estimated power storage amount Q, and the power storage amount Q is corrected. Thereafter, the electrical storage amount Q without estimated misalignment can be detected by adding or subtracting the electric quantity increased or decreased by charging and discharging with respect to the corrected electrical storage amount Q.

In this manner, in the secondary battery system 6 of the first embodiment, the electrical storage amount Q of each secondary battery 100 can be detected with high accuracy.

Further, even when it is determined that the state corresponding to the feature points B and C has been reached, the difference value is calculated in the same manner as when it is determined that the state corresponding to the feature point A described above has been reached, and based on the difference value, the battery controller ( The power storage amount Q of the secondary battery 100 estimated by 30 can be corrected. Thereby, the electrical storage quantity Q of each secondary battery 100 can be detected with high precision.

In the first embodiment, the battery controller 30 corresponds to dV / dQ calculating means, power storage amount estimating means, and power storage amount correcting means.

As shown in FIG. 3, the secondary battery 100 includes a rectangular sealed lithium ion secondary battery including a rectangular parallelepiped battery case 110, a positive electrode terminal 120, and a negative electrode terminal 130. to be. Among them, the battery case 110 is made of metal, and has a rectangular accommodating portion 111 that forms a rectangular accommodating space, and a metal lid portion 112. The electrode body 150, the positive electrode current collector member 122, the negative electrode current collector member 132, and the like are housed in the battery case 110 (the rectangular accommodating portion 111).

As shown in FIG. 4, the electrode body 150 has an elliptical cross section, and as shown in FIG. 5, the sheet-shaped positive electrode plate 155 (second electrode plate) and the negative electrode plate 156 ( It is a flat wound body formed by winding the first electrode plate) and the separator 157. The electrode body 150 is located at one end (right end in FIG. 3) in the axial direction (left and right direction in FIG. 3), and only a part of the positive electrode plate 155 overlaps in a spiral shape with a positive electrode winding part 155b. ) And the other end (left end in FIG. 3), and only a part of the negative electrode plate 156 has a negative electrode winding portion 156b overlapping in a spiral shape. The positive electrode mixture 152 including the positive electrode active material 153 (second active material) is coated on the positive electrode plate 155 except for the positive electrode winding portion 155b (see FIG. 5). Similarly, the negative electrode mixture 159 containing the negative electrode active material 154 (first active material) is applied to the negative electrode plate 156 at a portion other than the negative electrode wound portion 156b (see FIG. 5). The positive electrode winding portion 155b is electrically connected to the positive electrode terminal 120 through the positive electrode current collector member 122. The negative electrode winding portion 156b is electrically connected to the negative electrode terminal 130 through the negative electrode current collecting member 132.

In the first embodiment, LiFePO ₄ is used as the positive electrode active material 153. I use it. The positive electrode active material 153 is an active material which performs two-phase coexistence charge / discharge, and charge / discharge reaction is performed in the state where two crystals with different crystal structures coexist. The potential curve vs. Li of this positive electrode active material 153 is shown in FIG. 6.

In the first embodiment, a carbon material (specifically, natural graphite) is used as the negative electrode active material 154. Specifically, natural graphite having an average particle diameter of 20 µm, a lattice constant (C0) of 0.67 nm, a crystallite size (Lc) of 27 nm, and a graphitization degree of 0.9 or more is used. The negative electrode active material 154 is an active material with a phase change caused by charge and discharge, and the crystal structure is changed during charge and discharge. The potential curve vs. Li of this negative electrode active material 154 is shown in FIG. 7.

Next, the charging characteristic diagram of the secondary battery 100 is shown in FIG. 8 shows the battery voltage V when the secondary battery 100 is charged with a current of 1/5 C (the terminal between the positive electrode terminal 120 and the negative electrode terminal 130 in the first embodiment). Inter-voltage] behavior. In addition, the current value which can charge the theoretical electric capacity which the positive electrode active material 153 (LiFePO ₄ ) contained in the secondary battery 100 can theoretically accumulate as much as 1 C is set to 1C. Specifically, in the secondary battery 100, 1 C is about 700 mW.

As can be seen from FIG. 8, the secondary battery 100 is a battery voltage around 3.4V (3.3 to 3.5V), which corresponds to about 80% of the theoretical electric capacity (range of SOC 0 to 100% in FIG. 8). It can charge and discharge electric quantity. Therefore, in the secondary battery system 6 of the first embodiment, each secondary battery 100 is charged and discharged at a relatively high battery voltage of about 3.4 V over a capacity range of about 80% of the theoretical electric capacity. Therefore, high output can be obtained stably. In addition, the variation of the battery voltage V is 0.2 V or less (0.2 V in the first embodiment), and 50% or more of the theoretical capacitance (in this first embodiment, SOC 10 to 90%) A range of capacities that can be charged and discharged over a range) is set as a flat charge / discharge capacity range (FC).

9 has shown the Q-dV / dQ curve K which shows the relationship of the value of the electrical storage quantity Q with respect to the secondary battery 100, and the value of dV / dQ. The Q-dV / dQ curve K differentiates the battery voltage V into a storage amount Q corresponding thereto with respect to the function of the storage amount Q and the battery voltage V shown in FIG. 8. Obtained. Specifically, when generating the battery voltage curve of FIG. 8, the amount of power storage for each predetermined time is based on the amount of electricity storage Q and the battery voltage V obtained every predetermined time T (for example, 1 second). The value of dV / dQ which is the ratio of the change amount dV of the battery voltage V to the change amount dQ of (Q) is calculated, and the relationship between the value of this dV / dQ and the storage amount Q is shown in FIG. Indicated. As shown in FIG. 9, many characteristic points, such as feature point A (maximum point), feature point B (minimum point), and feature point C (maximum point), are shown by Q-dV / dQ curve K. As shown in FIG. In addition, the value of the battery voltage (V) in the characteristic points A, B, and C was 3.33V, 3.40V, and 3.43V in order.

By the way, as shown in FIG. 8, the secondary battery 100 has the flatness of which the fluctuation | variation of the value of battery voltage V is very small over the large capacity | capacitance range (SOC 10-90%) about 80% of theoretical electric capacity. It has a charge / discharge capacity range FC. Thus, in the case of the secondary battery with small fluctuation | variation of battery voltage over the wide capacity range of about 80% of theoretical electric capacity, there exists a possibility that it cannot detect the state of a secondary battery suitably.

However, as shown in FIG. 9, even in the flat charge / discharge capacity range FC where the fluctuation | variation of the value of battery voltage V is very small, the value of dV / dQ fluctuates largely. In the secondary battery system 6 of the first embodiment, since the state of the secondary battery 100 is detected using the value of dV / dQ that varies greatly, as described later, the secondary battery 100 can be accurately fixed. The state can be detected.

Next, a method of detecting the state of charge of the secondary battery 100 constituting the assembled battery 10 according to the first embodiment will be described. In addition, although the case where the secondary battery 100 is charged here is demonstrated as an example, the state of charge of the secondary battery 100 can be detected similarly when it discharges.

As shown in FIG. 10, first, in step S1, charging of the secondary battery 100 which comprises the assembled battery 10 is started by control of the battery controller 30. FIG. Subsequently, the procedure proceeds to step S2 where the voltage detection means 40 detects the battery voltage V of each secondary battery 100 and the secondary battery 100 is performed by the current detection means 50. The current value I flowing through is detected. In the first embodiment, the battery voltage V and the current value I are detected every predetermined time T (for example, 1 second).

Next, the flow advances to step S3, the current value I detected by the current detection means 50 is integrated, and the amount of charge electricity of each secondary battery 100 is calculated. Subsequently, the procedure proceeds to step S4, and the battery controller 30 estimates the amount of electricity (capacity Q stored) stored in each of the secondary batteries 100 from the calculated amount of charged electricity. In the first embodiment, the power storage amount Q for each predetermined time T is estimated based on the current value I detected for each predetermined time T (for example, one second).

Thereafter, the flow advances to step S5 to determine whether the estimated power storage amount Q has reached a predetermined power storage amount. When it is determined that the estimated power storage amount Q has reached a predetermined power storage amount (YES), charging is terminated.

On the other hand, when it is determined that the estimated power storage amount Q has not reached the predetermined power storage amount (“No”), the process proceeds to step S6 to determine the power storage amount Q for each of the secondary batteries 100. The value of dV / dQ which is the ratio of the change amount dV of the battery voltage V to the change amount dQ is calculated. In other words, the battery voltage V of the secondary battery 100 is differentiated by the electric storage quantity Q corresponding to this, and the value of dV / dQ is computed. Specifically, the battery voltage V for each predetermined time T is determined based on the battery voltage V and the power storage amount Q obtained for each predetermined time T with respect to each secondary battery 100. The change amount dQ of the change amount dV and the power storage amount Q is calculated, and the value of dV / dQ for each predetermined time T is calculated based on these changes.

Subsequently, the process proceeds to step S7 to determine whether the state corresponding to any one of the feature points A, B, and C on the Q-dV / dQ curve K has been reached for each secondary battery 100. Specifically, the battery controller 30 draws a Q-dV / dQ curve in real time based on the value of dV / dQ calculated for each predetermined time T, and the Q-dV / dQ curve and ROM ( By the contrast (pattern matching) of the Q-dV / dQ curve K (refer to FIG. 9) stored in 31), the secondary battery 100 has the characteristic points A, B, and C on the Q-dV / dQ curve. It is determined whether the state corresponding to which one has been reached.

When it is determined that none of the feature points A, B, and C have been reached (No), the process returns to Step S2 and the above-described processes of Steps S2 to S6 are performed.

On the other hand, if it is determined that any one of the feature points A, B, and C has been reached (YES), the process proceeds to step S8, from the feature reference value QK relating to the feature point, estimated by the battery controller 30 at this time. The difference value QK-QS is computed by subtracting the electrical storage quantity Q (made into the characteristic estimated value QS) of the secondary battery 100. FIG.

For example, when it is determined that the state corresponding to the feature point A has been reached, the battery controller 30 is reached when the feature point A is reached from the feature reference value QKA at the feature point A stored in the ROM 31. The difference value QKA-QSA is computed by subtracting the electrical storage quantity Q (characteristic estimated value QSA) of the secondary battery 100 estimated by this.

Subsequently, the flow advances to step S9 to determine whether the absolute value of the difference value is larger than 0.1 Ah. When the absolute value of the difference value (QK? QS) at any one of the feature points A, B, and C is larger than 0.1 Ah, the estimation of the electrical storage amount in the secondary battery system 6 is not a simple measurement error. It can be regarded as a misalignment. Therefore, in the first embodiment, it is determined whether or not the estimated shift of the electrical storage amount in the secondary battery system 6 has occurred by whether or not the absolute value of the difference values QK? QS is larger than 0.1 Ah. I'm trying to.

In step S9, when it is determined that the absolute value of the difference value QK-QS is 0.1 Ah or less (No), it returns to step S2 again and performs the process to steps S2 to S8 mentioned above.

On the other hand, when it is determined in step S9 that the absolute value of the difference values QK-QS is greater than 0.1Ah ("Yes"), the process proceeds to step SA and the battery controller 30 by the difference value QK-QS. The amount of power storage Q of the secondary battery 100 estimated by () is corrected. Specifically, the difference value QK-QS is added to the estimated power storage amount Q, and the power storage amount Q is corrected. For example, when it is determined that the state corresponding to the feature point A has been reached, and the difference value QKA-QSA is 0.2 Ah, the difference value 0.2 (Ah) is added to the estimated power storage amount Q and the power storage amount ( Correct Q).

After that, the process returns to step S2 again, and the processes from steps S2 to S4 described above are performed. Thereby, in step S4, the charged electricity amount calculated by current integration is added to the corrected power storage amount Q, and the power storage amount Q without estimated misalignment can be detected. In this manner, in the secondary battery system 6 of the first embodiment, the electrical storage amount Q of each secondary battery 100 can be detected with high accuracy.

After that, in step S5, when it is determined that the electrical storage amount Q has reached the predetermined electrical storage amount (YES), charging is terminated.

Here, the manufacturing method of the secondary battery 100 of this 1st Example is demonstrated.

First, LiFePO ₄ [positive electrode active material 153], acetylene black (conductive aid), and polyvinylidene fluoride (binder resin) are mixed in a ratio of 85: 5: 10 (weight ratio), and to this is N-methylpyrroli. Pig (dispersion solvent) was mixed to prepare a positive electrode slurry. Subsequently, after apply | coating this positive electrode slurry to the surface of the aluminum foil 151, and drying, it press-processed. This obtained the positive electrode plate 155 in which the positive electrode mixture 152 was coated on the surface of the aluminum foil 151 (see FIG. 5).

In addition, natural graphite [negative electrode active material 154], styrene-butadiene copolymer (binder resin), and carboxymethyl cellulose (thickener) were mixed in water at a ratio of 95: 2.5: 2.5 (weight ratio) to prepare a negative electrode slurry. Was produced. Subsequently, after apply | coating this negative electrode slurry to the surface of the copper foil 158, and drying, it press-processed. This obtained the negative electrode plate 156 in which the negative electrode mixture 159 was coated on the surface of the copper foil 158 (see FIG. 5). In the first embodiment, as the negative electrode active material 154, natural graphite having an average particle diameter of 20 µm, a lattice constant (C0) of 0.67 nm, a crystallite size (Lc) of 27 nm, and a graphitization degree of 0.9 or more is used. In the first embodiment, the application amounts of the positive electrode slurry and the negative electrode slurry are adjusted so that the ratio of the theoretical capacity of the positive electrode to the theoretical capacity of the negative electrode is 1: 1.5.

Next, the positive electrode plate 155, the negative electrode plate 156, and the separator 157 were stacked and wound up to form an electrode body 150 having an elliptical cross section (see FIGS. 4 and 5). However, when laminating the positive electrode plate 155, the negative electrode plate 156, and the separator 157, the positive electrode mixture 152 of the positive electrode plate 155 is not applied from one end of the electrode body 150. The positive electrode plate 155 is disposed so that the uncoated construction part protrudes. Moreover, the negative electrode plate 156 is arrange | positioned so that the uncoated construction part which does not apply the negative electrode mixture 159 in the negative electrode plate 156 may protrude from the opposite side to the uncoated part of the positive electrode plate 155. Thereby, the electrode body 150 (refer FIG. 3) which has the positive electrode winding part 155b and the negative electrode winding part 156b is formed. In addition, in the first embodiment, a polypropylene / polyethylene / polypropylene three-layer structure composite porous membrane is used as the separator 157.

Next, the positive electrode winding portion 155b and the positive electrode terminal 120 of the electrode body 150 are connected via the positive electrode current collector member 122. In addition, the negative electrode winding portion 156b of the electrode body 150 and the negative electrode terminal 130 are connected through the negative electrode current collecting member 132. Then, this was accommodated in the rectangular accommodating part 111, the square accommodating part 111 and the cover 112 were welded, and the battery case 110 was sealed. Subsequently, after pouring the electrolyte through a pouring hole (not shown) provided in the lid 112, the secondary battery 100 of the first embodiment is completed by sealing the pouring hole. In the first embodiment, 1 mol of lithium hexafluorophosphate (LiPF ₆ ) is dissolved in a solution in which EC (ethylene carbonate) and DEC (diethyl carbonate) are mixed at 4: 6 (volume ratio) as the electrolyte. Doing.

(Second Embodiment)

In the second embodiment, as shown in FIG. 11, the secondary battery 100 (single cell), the voltage detecting means 40, the current detecting means 50, and the battery controller 30 are provided. A secondary battery system 16 was prepared. About this secondary battery system 16, the evaluation test of the state detection precision was done.

Specifically, the battery was discharged until the battery voltage of the secondary battery 100 became 2.5 V, and then charged at a current value of 1 / 5C. At this time, similarly to steps S2 to S6 of the first embodiment, while detecting the battery voltage V and the current value I every predetermined time, the power storage amount Q is estimated by current integration, and the power storage amount Q and The value of dV / dQ was calculated based on the battery voltage (V).

In the second embodiment, the monitor displays a Q-dV / dQ curve (see Fig. 9) showing the relationship between the value of power storage quantity Q and the value of dV / dQ in real time. Charging was stopped when the Q-dV / dQ curve drawn on this monitor was visually observed and judged that the characteristic point A was reached. Thereafter, the secondary battery 100 was subjected to constant current discharge at a current value of 1 / 5C until the battery voltage became 2.5V. The discharge capacity at this time was acquired as electrical storage quantity QA1.

In addition, four other secondary batteries 100 were prepared, each embedded in the secondary battery system 16, and charged until reaching the characteristic point A as described above, and then discharged. The discharge capacity of each secondary battery 100 at this time was acquired as electrical storage quantity QA2-QA5. Thereafter, the values of power storage amounts QA1 to QA5 were divided by the theoretical electric capacity of the secondary battery 100, and converted into values of SOC (%). These maximum value, minimum value, and average value are shown graphically in FIG.

In Fig. 12, the maximum value is indicated by a broken line, the minimum value by a dashed-dot line, and the average value by a solid line.

Similarly, power storage amounts (QB1 to QB5) when charged until it is determined that the feature point B is reached, and power storage amounts (QC1 to QC5) when charged until it is determined that the feature point C is reached are obtained. . Thereafter, the values of power storage amounts (QB1 to QB5 and QC1 to QC5) were respectively divided by theoretical capacitance, and converted into values of SOC (%). These maximum value, minimum value, and average value are also shown by the graph in FIG.

In addition, the value of the battery voltage when reaching the characteristic points A, B, and C was 3.33V, 3.40V, and 3.43V in order.

Moreover, as a comparative example, the secondary battery system which estimates the electrical storage quantity Q of the secondary battery 100 based on the battery voltage V of the secondary battery 100 was prepared. After discharging until the battery voltage of the secondary battery 100 becomes 2.5V, the battery voltage V corresponds to the characteristic point A for the secondary battery 100 using this secondary battery system. Charging was carried out at a current value of 1 / 5C until the voltage reached 3.33V. Thereafter, the secondary battery 100 was subjected to constant current discharge at a current value of 1 / 5C until the battery voltage became 2.5V. The discharge capacity at this time was acquired as electrical storage quantity QA11.

In addition, discharge capacity was similarly acquired about four other secondary batteries 100, and these were made into electrical storage quantities QA12-QA15. Thereafter, the values of power storage amounts QA11 to QA15 were divided by the theoretical capacitance of the secondary battery 100, and converted into values of SOC (%). These maximum value, minimum value, and average value are shown graphically in FIG.

Similarly, the storage capacity QB11 to QB15 and the characteristic point C when the secondary battery 100 is charged until the battery voltage V becomes the battery voltage 3.40 V corresponding to the characteristic point B are also supported. The electrical storage amounts QC11 to QC15 when charged until the battery voltage reached 3.43 V were obtained. Thereafter, the values of power storage amounts (QB11 to QB15 and QC11 to QC15) were respectively divided by theoretical capacitance, and converted into values of SOC (%). These maximum value, minimum value, and average value are also shown by the graph in FIG.

Here, the state detection precision of the secondary battery system 16 of the 2nd Example and the state detection precision of the secondary battery system of a comparative example are compared and examined with reference to FIG.

First, comparing the graph concerning the characteristic point A, in 2nd Example, the maximum difference GA1 (difference between a maximum value and a minimum value) of the electrical storage quantities QA1-QA5 was about 3% in SOC conversion. On the other hand, in the comparative example, the maximum difference GA2 (difference between the maximum value and the minimum value) of the electrical storage amounts QA11 to QA15 became about 7% in terms of SOC, and the deviation was larger than in the second embodiment. From this result, it can be said that the second embodiment can detect the state of charge of the secondary battery with higher accuracy than that of the comparative example.

In addition, when comparing the graph regarding the characteristic point B, in 2nd Example, the maximum difference GB1 (difference between a maximum value and a minimum value) of the electrical storage quantities QB1-QB5 was about 3% in SOC conversion. On the other hand, in the comparative example, the maximum difference GB2 (difference between the maximum value and the minimum value) of the power storage amounts QB11 to QB15 became about 9% in SOC conversion, and the deviation was larger than in the second embodiment. From this result, it can be said that the second embodiment can detect the state of charge of the secondary battery with higher accuracy than that of the comparative example.

In addition, when comparing the graph concerning the characteristic point C, in 2nd Example, the largest difference GC1 (difference between a maximum value and a minimum value) of the electrical storage quantities QC1 to QC5 was about 3% in SOC conversion. On the other hand, in the comparative example, the maximum difference GC2 (difference between the maximum value and the minimum value) of the electric storage quantities QC11-QC15 became about 9% in SOC conversion, and the deviation became large compared with 2nd Example. From this result, it can be said that the second embodiment can detect the state of charge of the secondary battery with higher accuracy than that of the comparative example.

From the above result, it can be said that the secondary battery system 16 of 2nd Example can detect the state of a secondary battery with high precision. This is because in the secondary battery system 16 of the second embodiment, the state of the secondary battery 100 is detected using a value of dV / dQ that varies greatly with respect to the battery voltage V. FIG. For this reason, even in the capacity | capacitance range (SOC 10 to 90%) where the fluctuation | variation of the value of the battery voltage V of the secondary battery 100 is very small, the state of the secondary battery 100 can be detected with high precision.

(Third Embodiment)

In the third embodiment, first, a plurality of secondary batteries 100 are subjected to a deterioration test (preservation deterioration test, cycle deterioration test) under various conditions to be described later, and the plurality of secondary batteries 100 having different degrees of deterioration. ) Was prepared.

(Preservation deterioration test)

First, 72 secondary batteries 100 were prepared. Subsequently, each secondary battery 100 was discharged at a current value of 1/3 C until the battery voltage reached 2.5 V, so that SOC was 0%. Thereafter, 72 secondary batteries 100 were divided into six groups (first to sixth groups) of 12 units each.

Among these, about 12 secondary batteries 100 which belong to a 1st group were made into the state which is SOC 0%, without charging. In addition, the 12 secondary batteries 100 belonging to the second group were charged at a current value of 1 / 5C to make SOC 20%. In addition, about twelve secondary batteries 100 belonging to the third group were charged at a current value of 1 / 5C to be SOC 40%. In addition, about twelve secondary batteries 100 belonging to the fourth group were charged at a current value of 1 / 5C to be SOC 60%. In addition, about twelve secondary batteries 100 belonging to the fifth group were charged at a current value of 1 / 5C to be SOC 80%. In addition, about twelve secondary batteries 100 belonging to the sixth group were charged at a current value of 1 / 5C to be SOC 100%.

Subsequently, in each of the first to sixth groups, four were divided into three groups (Group A, Group B, Group C). And the total of 24 secondary batteries 100 which belong to group A of each group were preserve | saved for two weeks in the thermostat maintained at the temperature of 0 degreeC. In addition, a total of 24 secondary batteries 100 belonging to group B of each group were stored for 2 weeks in a thermostat maintained at a temperature of 30 ° C. In addition, a total of 24 secondary batteries 100 belonging to group C of each group were stored for two weeks in a thermostat maintained at a temperature of 60 ° C. In this manner, secondary batteries 100 having different SOCs of 0, 20, 40, 60, 80, and 100% were stored in different thermostats at different temperatures of 0, 30, and 60 ° C for 2 weeks, respectively, to promote deterioration. .

(Cycle deterioration test)

First, four thermostats in which the temperature inside a tank differs by -30 degreeC, 0 degreeC, 30 degreeC, and 60 degreeC were prepared. Subsequently, eight secondary batteries 100 were arranged in each thermostatic chamber, and cycle charging and discharging were performed on each secondary battery 100. Specifically, 200 cycles of charge and discharge were performed at a current value of 2C, with a charge upper limit voltage value of 4.1 V and a discharge lower limit voltage value of 2.5 V. In this manner, cycle charging and discharging were performed at four different environmental temperatures to promote deterioration of the secondary battery 100.

Next, about the secondary battery 100 which performed the above-mentioned storage degradation test or cycle degradation test, the battery capacity (full charge capacity) was measured as follows. First, each secondary battery 100 was charged at a current value of 1 / 5C until the battery voltage reached 4.1V. Thereafter, charging was performed at a constant voltage of 4.1 V, and charging was terminated when the current value dropped to the initial 1/10. Thereafter, discharge was performed for each secondary battery 100 until the battery voltage reached 2.5V at a current value of 1 / 5C. The discharge capacity at this time was measured as the battery capacity (full charge capacity) of each secondary battery 100. At this time, in the same manner as in the first embodiment, Q-dV / dQ curves were acquired for each secondary battery 100. One of these is shown in FIG.

In addition, the battery capacity (full charge capacity) was measured as mentioned above about the secondary battery 100 of the initial state which has not performed the deterioration test. At this time, the Q-dV / dQ curve was acquired about the secondary battery 100 of an initial state similarly to 1st Example. This is shown in FIG.

In addition, the secondary battery 100 in which no short circuit occurred was prepared, and the battery capacity (full charge capacity) was also measured as described above. At this time, the Q-dV / dQ curve was acquired about the secondary battery 100 of an initial state similarly to 1st Example.

Here, the Q-dV / dQ curve (refer to FIG. 14) of the secondary battery 100 in an initial state, and the Q-dV / of the secondary battery 100 whose battery capacity (full charge capacity) was reduced by the deterioration test. Compare the dQ curves (see FIG. 13). As can be seen by comparing the curves of Figs. 13 and 14, both curves show three local maxima and four local minima. Among these, the maximum point which appears first from the one with a smaller battery voltage is the characteristic point A, and the maximum point which appears 3rd is made into the characteristic point C.

First, in FIG. 14, the difference value [Delta] Q1 (= QC1? QA1) between the value QA1 of the power storage amount at the feature point A and the value QC1 of the power storage amount at the feature point C is calculated. In Fig. 13, the difference value [Delta] Q2 (= QC2-QA2) between the value QA2 of the power storage amount at the feature point A and the value QC2 of the power storage amount at the feature point C is calculated.

Comparing ΔQ1 and ΔQ2, it can be seen that ΔQ1> ΔQ2. That is, the secondary battery 100 whose capacity is lowered (full charge capacity is lowered) than the secondary battery 100 in the initial state has the value QA of the electric storage amount at the feature point A and the feature point C. It can be seen that the difference value ΔQ of the value QC of the power storage amount decreases.

Thus, with respect to each secondary battery 100 which performed the deterioration test, and the secondary battery 100 which the internal short circuit generate | occur | produced, the value QA of the electrical storage quantity in the characteristic point A and the characteristic point C The difference value ΔQ of the value QC of the electrical storage amount was calculated. This result is shown in FIG. 15 as a graph which shows the relationship between battery capacity (mAh) and (DELTA) Q. In FIG. 15, the secondary battery 100 in the initial state is represented by ◆, and the secondary battery 100 having reduced capacity (five secondary batteries 100 selected from the secondary battery 100 subjected to the deterioration test) is shown. (Circle) and the secondary battery 100 which the internal short circuit generate | occur | produced is shown by (triangle | delta).

As shown in FIG. 15, as the battery capacity (full charge capacity) decreases, the difference value ΔQ between the value QA of the power storage amount at the feature point A and the value QC of the power storage amount at the feature point C decreases. I can see it goes. In addition, in the secondary battery 100 in which internal short circuit has occurred, it can be seen that the difference value ΔQ is extremely small.

In the third embodiment, using such characteristics, the battery capacity (full charge capacity) of the secondary battery 100 is lowered and the internal beauty is based on the difference value ΔQ in the Q-dV / dQ curve. Detect shorts.

Compared with the secondary battery system 6 of the first embodiment, the secondary battery system of the third embodiment differs only in the battery controller and is otherwise identical. Therefore, the differences from the first embodiment will be mainly described here, and the description of the same points will be omitted or simplified.

As shown in FIG. 16, the secondary battery system 26 of the third embodiment includes an assembled battery 10 in which a plurality of secondary batteries 100 (single cells) are electrically connected in series with each other, and voltage detection is performed. The means 40, the current detection means 50, and the battery controller 130 are provided. The battery controller 130 has a ROM 131, a CPU 132, a RAM 133, and the like.

Similar to the battery controller 30 of the first embodiment, the battery controller 130 estimates the electrical storage amount Q of each secondary battery 100 by current integration every predetermined time T. FIG. In addition, the battery controller 130 acquires the battery voltage V of each secondary battery 100 detected by the voltage detecting means 40 every predetermined time T in synchronization with the current integration. In addition, the battery controller 130 calculates the value of dV / dQ for each predetermined time T, similarly to the battery controller 30 of the first embodiment.

In addition, Q- which shows the relationship between the value of the electrical storage quantity Q and the value of dV / dQ acquired with respect to the secondary battery 100 of the initial state which is not deteriorated in ROM 131 of the battery controller 130 previously. The dV / dQ curve K (see Fig. 9) is stored. In addition, the value of the electrical storage amount Q at the characteristic point A (maximum point) on the Q-dV / dQ curve K (set as the characteristic reference value QKA) and the electrical storage amount Q at the characteristic point C (maximum point) ) Is stored in the ROM 131. The difference value? Q (referred to as the reference difference value? QK) of the value of the?

In addition, the battery controller 130 draws a Q-dV / dQ curve in real time based on the value of dV / dQ calculated for each predetermined time T, and stores the Q-dV / dQ curve in the ROM 131. Due to the contrast (pattern matching) of the Q-dV / dQ curve K (see FIG. 9), the secondary battery 100 is in a state corresponding to the feature point A or the feature point C on the Q-dV / dQ curve. It is determined whether it has reached.

For example, when it is determined that the state corresponding to the feature point A has been reached, when the feature point A is reached, the storage capacity Q of the secondary battery 100 estimated by the battery controller 130 (feature estimation value QSA) Remember]. In addition, when it determines with having reached | attained the state corresponding to the characteristic point C, when it reaches the characteristic point C, it is set as the electrical storage quantity Q (characteristic estimated value QSC) of the secondary battery 100 estimated by the battery controller 130. Remember. And the difference value (DELTA) Q (actual difference value (DELTA QS) = QSC-QSA) which subtracted the feature estimation value QSA from the feature estimation value QSC is calculated.

In addition, the battery controller 130 contrasts the calculated difference value DELTA QS and the reference difference value DELTA QK. When the measured difference DELTA QS is smaller than the reference difference DELTA QK, it is determined that the battery capacity of the secondary battery 100 is lowered. In particular, when the measured difference DELTA QS is less than 60% of the reference difference DELTA QK, it is determined that an internal short circuit occurs in the secondary battery 100. In this case, the battery controller 130 outputs a signal indicating that the secondary battery 100 is abnormal and prompts replacement of the secondary battery 100.

In the third embodiment, the battery controller 130 corresponds to the dV / dQ calculating means, the power storage amount estimating means, the deterioration detecting means (capacity drop detecting means), and the abnormality detecting means (non-short detection means).

Next, a description will be given of a state detection method of the secondary battery 100 constituting the assembled battery 10 according to the third embodiment. In addition, it demonstrates here as an example when charging the secondary battery 100. FIG. In addition, about step S1 to S6, since it is the same as that of 1st Example, description is abbreviate | omitted.

As shown in FIG. 17, after performing the process of step S1-S6, it progresses to step T7 and the state detection is performed for each secondary battery 100. FIG. Proceeding to the subroutine shown in FIG. 18, first, in step T71, it is determined whether the state corresponding to the feature point A on the Q-dV / dQ curve has been reached for each secondary battery 100. FIG. Specifically, a Q-dV / dQ curve is drawn in real time based on the value of dV / dQ calculated for each predetermined time T by the battery controller 130, and the Q-dV / dQ curve and the ROM 131 are used. By the contrast (pattern matching) of the Q-dV / dQ curve K (refer to FIG. 9) stored in), the secondary battery 100 is in a state corresponding to the feature point A on the Q-dV / dQ curve. It is determined whether it has reached.

If it is determined that the feature point A has not been reached (“No”), the process returns to the main routine shown in FIG. 17, and the processes of steps S2 to T7 are performed again.

On the other hand, if it is determined that the feature point A has been reached (YES), the process proceeds to step T72 where the power storage amount Q of the secondary battery 100 estimated by the battery controller 130 when the feature point A has been reached [characteristic] Estimated value QSA].

Next, the flow advances to step T73 to determine whether the state corresponding to the feature point C on the Q-dV / dQ curve K has been reached for each secondary battery 100. Specifically, a Q-dV / dQ curve is drawn in real time based on the value of dV / dQ calculated for each predetermined time T by the battery controller 130, and the Q-dV / dQ curve and the ROM 131 are used. By the contrast (pattern matching) of the Q-dV / dQ curve K (refer to FIG. 9) stored in the), the secondary battery 100 is in a state corresponding to the characteristic point C on the Q-dV / dQ curve. It is determined whether it has reached.

When it is determined that the feature point C has not been reached (“No”), the process returns to the main routine shown in FIG. 17, and the processing of steps S2 to T7 is performed again.

On the other hand, if it is determined that the feature point C has been reached (YES), the process proceeds to step T74 where the power storage amount Q of the secondary battery 100 estimated by the battery controller 130 when the feature point C is reached [characteristic] Estimated value QSC].

Subsequently, the flow advances to step T75 to calculate the difference value? Q (actual difference value? QS = QSC? QSA) obtained by subtracting the feature estimate value QSA from the feature estimate value QSC.

After that, the flow advances to step T76 to compare the calculated actual difference value ΔQS and the reference difference value ΔQK stored in the ROM 131. Specifically, the measured difference value ΔQS is divided by the reference difference value ΔQK to calculate the value of ΔQS / ΔQK.

Subsequently, the process proceeds to step T77 to determine whether or not the relationship of? QS /? QK <1 is satisfied. That is, it is determined whether the measured difference value? QS is smaller than the reference difference value? QK. If it is determined that ΔQS / ΔQK <1 is not satisfied (“No”), the process returns to the main routine shown in FIG. 17, and the processing of steps S2 to T7 is performed again.

On the other hand, when it is determined that (DELTA) QS / ΔQK <1 is satisfied (YES), it progresses to step T78 and it determines whether the relationship of (DELTA) QS / (DELTA) QK≥0.6 is satisfied. That is, it is determined whether the measured difference value ΔQS is 60% or more of the reference difference value ΔQK.

If it is determined in step T78 that ΔQS / ΔQK ≧ 0.6 is satisfied (“Yes”), the flow proceeds to step T79 to determine that the battery capacity (full charge capacity) of the secondary battery 100 is reduced. .

On the other hand, when it is determined that ΔQS / ΔQK ≧ 0.6 is not satisfied (“No”), the process proceeds to step T7A to determine that the secondary battery 100 is abnormal, and specifically to the secondary battery 100. An internal short circuit has occurred. In this case, the flow advances to step T7B to output a signal indicating that the secondary battery 100 is abnormal and prompts replacement of the secondary battery 100.

Subsequently, the process returns to the main routine shown in FIG. 17, and the processes of steps S2 to T7 are performed. After that, in step S5, when it is determined that the electrical storage amount Q has reached the predetermined electrical storage amount (YES), charging is terminated.

(Fourth Embodiment)

For the secondary battery 100 subjected to the storage deterioration test or the cycle deterioration test in Example 3, the internal resistance (mΩ) was measured as follows, respectively.

First, for each secondary battery 100, discharge was performed until the battery voltage reached 2.5V at a current value of 1 / 3C. Thereafter, charging was performed at a current value of 1 / 5C to obtain SOC of 50%. In this state, the internal resistance of each secondary battery 100 was measured by the AC impedance method. Specifically, the frequency was changed from 1 MHz to 1 kHz while using a 1252A manufactured by Sotlan Corp. as a FRA (frequency response analyzer) and SI1287 manufactured by Sotlan Corp. as a control unit, while giving a potential amplitude of 5 mV. The value measured when the frequency was 1 Hz was taken as the internal resistance value (mΩ) of the secondary battery 100.

In addition, for each secondary battery 100 subjected to the deterioration test in the third embodiment, the battery capacity (full charge capacity) was measured in the same manner as in the third embodiment, and at this time, the battery controller 230 every predetermined time Based on the value of dV / dQ calculated, the V-dV / dQ curve which shows the relationship of the value of battery voltage (V) and the value of dV / dQ was acquired. One of these is shown in FIG. Moreover, the V-dV / dQ curve was acquired also about the secondary battery 100 of the initial state which has not performed the deterioration test. This is shown in FIG.

In addition, the battery capacity (full charge capacity) was measured similarly to the 3rd Example in the state which made the secondary battery 100 of the initial state which is not performing the deterioration test into poor connection, and was measured by the battery controller 230 at this time. The V-dV / dQ curve was acquired based on the value of dV / dQ calculated every predetermined time.

In the fourth embodiment, the cable 127 for connecting the battery controller 230 and the like to the positive electrode terminal 120 of the secondary battery 100 is connected as follows. As shown in FIG. 25, in the state which penetrated the through-hole 120c of the positive electrode terminal 120 and the through-hole 127c of the connection terminal 127b, the bolt part 125b of the bolt 125 was penetrated. The nut 126 is screwed to the threaded portion 125b of 125 to fasten the positive electrode terminal 120 and the connection terminal 127b. Thereby, the positive electrode terminal 120 and the connection terminal 127b can be brought into close contact with each other, whereby the two can be appropriately connected. Therefore, in the fourth embodiment, the nut 126 is loosened and the positive electrode terminal 120 and the connection terminal 127b are not in close contact, thereby making the connection poor.

Here, the V-dV / dQ curve of the secondary battery 100 in the initial state (see FIG. 20) and the V-dV / dQ curve of the secondary battery 100 in which the internal resistance increased by the deterioration test (see FIG. 19). ). As can be seen by comparing the curves of FIG. 19 and FIG. 20, the three maximum points are shown for both curves. Among these, the maximum point that appears first when the battery voltage is smaller is referred to as the feature point D and the maximum point that appears third is the feature point E.

First, in FIG. 20, the difference value [Delta] V1 (= VE1-VD1) between the value VD1 of the battery voltage at the feature point D and the value VE1 of the battery voltage at the feature point E is calculated. Moreover, in FIG. 19, the difference value ((DELTA) V2 (= VE2-VD2)) of the value VD2 of the battery voltage in the characteristic point D, and the value VE2 of the battery voltage in the characteristic point E is calculated.

Comparing ΔV1 and ΔV2, it can be seen that ΔV2> ΔV1. That is, the value of the battery voltage at the feature point D and the value of the battery voltage at the feature point E are higher than those of the secondary battery 100 in which the internal resistance is higher than the secondary battery 100 in the initial state. It can be seen that the difference value ΔV of VE) becomes large.

In this manner, the values VD of the battery voltage at the feature point D and the values of the battery voltage at the feature point E for each of the secondary batteries 100 subjected to the deterioration test and the secondary battery 100 with poor connection. The difference value (ΔV) of (VE) was calculated. This result is shown in FIG. 21 as a graph which shows the relationship between internal resistance mAh and (DELTA) V. In addition, in FIG. 21, the secondary battery 100 of an initial state is ◆, and the secondary battery 100 which internal resistance increased (five secondary batteries 100 selected from the secondary battery 100 which performed the deterioration test). (Circle) and the defective secondary battery 100 are shown by (triangle | delta).

21, as the internal resistance of the secondary battery 100 increases, the difference value ΔV between the value VD of the battery voltage at the feature point D and the value VE of the battery voltage at the feature point E is determined. You can see that it grows. In addition, in the secondary battery 100 of connection failure, it can be seen that the difference value ΔV becomes extremely large.

In the fourth embodiment, using this characteristic, the rise of the internal resistance of the secondary battery 100 and the connection failure are detected based on the difference value ΔV in the V-dV / dQ curve.

Compared with the secondary battery system 6 of the first embodiment, the secondary battery system of the fourth embodiment differs only in the battery controller, and is otherwise identical. Therefore, the differences from the first embodiment will be mainly described here, and the description of the same points will be omitted or simplified.

As shown in FIG. 22, the secondary battery system 36 of the fourth embodiment includes a battery pack 10 in which a plurality of secondary batteries 100 (single cells) are electrically connected in series with each other, and voltage detection is performed. The means 40, the current detection means 50, and the battery controller 230 are provided. The battery controller 230 has a ROM 231, a CPU 232, a RAM 233, and the like.

Like the battery controller 30 of the first embodiment, the battery controller 230 estimates the electrical storage amount Q of each secondary battery 100 by current integration every predetermined time T. FIG. In addition, the battery controller 230 acquires the battery voltage V of each secondary battery 100 detected by the voltage detecting means 40 every predetermined time T in synchronization with the current integration. In addition, the battery controller 230 calculates the value of dV / dQ for each predetermined time T, similarly to the battery controller 30 of the first embodiment.

In addition, in the ROM 231 of the battery controller 230, V-dV / dQ indicating a relationship between the value of the battery voltage V and the value of dV / dQ acquired for the secondary battery 100 in the initial state in advance. The curve L (see FIG. 26) is stored. Further, the value of the battery voltage V at the feature point D on the V-dV / dQ curve L (referred to as the reference voltage value VKD) and the value of the battery voltage V at the feature point E (reference) The difference value ΔV (which is referred to as the reference difference value ΔVK) of the voltage value VKE] is stored in the ROM 231.

In addition, the battery controller 230 draws a V-dV / dQ curve in real time based on the value of dV / dQ calculated for each predetermined time T, to the V-dV / dQ curve and the ROM 231. By contrast (pattern matching) of the stored V-dV / dQ curve L (see FIG. 26), the secondary battery 100 is in a state corresponding to the feature point D or E on the V-dV / dQ curve. It is determined whether it has reached.

For example, when it is determined that the state corresponding to the feature point D has been reached, the battery voltage (actual voltage value VSD) of the secondary battery 100 detected by the voltage detecting means 40 when the feature point D is reached. Remember. Further, even when it is determined that the state corresponding to the feature point E has been reached, the battery voltage of the secondary battery 100 detected by the voltage detecting means 40 when the feature point E has been reached (actual voltage value VSE). Remember. The difference value ΔV (measured difference value ΔVS = VSE? VSD) is calculated by subtracting the actual voltage value VSD from the actual voltage value VSE.

In addition, the battery controller 230 contrasts the calculated measured difference value ΔVS and the reference difference value ΔVK. When the measured difference value ΔVS is larger than the reference difference value ΔVK, it is determined that the internal resistance of the secondary battery 100 is rising. In particular, when the measured difference value ΔVS is larger than three times the reference difference value ΔVK, it is determined that a poor connection of the secondary battery 100 has occurred. In this case, the battery controller 230 outputs a signal indicating that a poor connection of the secondary battery 100 has occurred, and prompts the connection confirmation of the secondary battery 100.

In the fourth embodiment, the battery controller 230 corresponds to the dV / dQ calculating means, the power storage amount estimating means, the deterioration detecting means (resistance rising detecting means) and the abnormality detecting means (connection failure detecting means).

Next, the state detection method of the secondary battery 100 constituting the assembled battery 10 according to the fourth embodiment will be described. In addition, it demonstrates here as an example when charging the secondary battery 100. FIG. In addition, about step S1 to S6, since it is the same as that of 1st Example, description is abbreviate | omitted.

As shown in FIG. 23, after performing the process of step S1-S6, it progresses to step U7 and the state detection is performed with respect to each secondary battery 100. FIG. Proceeding to the subroutine shown in FIG. 24, first, in step U71, it is determined whether or not the state corresponding to the feature point D on the V-dV / dQ curve has been reached for each secondary battery 100. FIG. Specifically, the battery controller 230 draws a V-dV / dQ curve in real time based on the value of dV / dQ calculated for each predetermined time T, and the V-dV / dQ curve and ROM ( Due to the contrast (pattern matching) of the V-dV / dQ curve L (see FIG. 26) stored in 231, the secondary battery 100 corresponds to the feature point D on the V-dV / dQ curve. It is determined whether or not to reach.

When it is determined that the feature point D has not been reached (“No”), the process returns to the main routine shown in FIG. 23, and the processes of steps S2 to U7 are performed again.

On the other hand, if it is determined that the feature point D has been reached (YES), the process proceeds to step U72 where the battery voltage value of each secondary battery 100 detected by the voltage detecting means 40 when the feature point D is reached (actual measurement). Voltage value VSD].

Subsequently, the procedure proceeds to step U73 to determine whether the state corresponding to the feature point E on the V-dV / dQ curve has been reached for each secondary battery 100. Specifically, a V-dV / dQ curve is drawn in real time based on the value of dV / dQ calculated by the battery controller 230 for each predetermined time T, and the V-dV / dQ curve and the ROM 231 are shown. By the contrast (pattern matching) of the V-dV / dQ curve L (refer to FIG. 26) stored in), the secondary battery 100 is in a state corresponding to the feature point E on the V-dV / dQ curve. It is determined whether it has reached.

If it is determined that the feature point E has not been reached (“No”), the process returns to the main routine shown in FIG. 23, and the processes of steps S2 to U7 are performed again.

On the other hand, if it is determined that the feature point E has been reached (YES), the process proceeds to step U74, where the battery voltage value of each secondary battery 100 detected by the voltage detecting means 40 when the feature point E is reached (actual measurement). Voltage value VSE].

Subsequently, the procedure proceeds to step U75 to calculate the difference value? V (actual difference value? VS = VSE? VSD) obtained by subtracting the measured voltage value VSD from the measured voltage value VSE.

Subsequently, the procedure proceeds to step U76 to compare the calculated actual difference value ΔVS and the reference difference value ΔVK stored in the ROM 231. Specifically, the measured difference value ΔVS is divided by the reference difference value ΔVK to calculate the value of ΔVS / ΔVK.

Subsequently, the process proceeds to step U77 to determine whether or not ΔVS / ΔVK> 1 is satisfied. That is, it is determined whether the measured difference value ΔVS is larger than the reference difference value ΔVK. When it is determined that ΔVS / ΔVK> 1 is not satisfied (“No”), the process returns to the main routine shown in FIG. 23, and the processes of steps S2 to U7 are performed again.

On the other hand, when it determines with (DELTA) VS / (DELTA) VK> 1 (YES), it progresses to step U78 and determines whether it meets (DELTA) VS / (DELTA) VK> 3. That is, it is determined whether the measured difference value ΔVS is greater than three times the reference difference value ΔVK.

When it is determined in step U78 that ΔVS / ΔVK> 3 is not satisfied (“No”), the process proceeds to step U79 to determine that the internal resistance of the secondary battery 100 is rising.

On the other hand, when it determines with (DELTA) VS / (DELTA) VK> 3 (Yes), it progresses to step U7A and it determines with the bad connection of the secondary battery 100 having generate | occur | produced. In this case, it progresses to step U7B and outputs the signal that the connection failure of the secondary battery 100 has generate | occur | produced, and prompts the connection confirmation of the secondary battery 100.

Subsequently, the process returns to the main routine shown in FIG. 23 to perform the processing of steps S2 to U7. Subsequently, in step S5, when it is determined that the power storage amount Q has reached the predetermined power storage amount (YES), charging is terminated.

As mentioned above, although this invention was demonstrated based on the 1st-4th Example, this invention is not limited to the said Example, It is possible to change suitably and to apply it in the range which does not deviate from the summary. Of course.

For example, in the third embodiment, the state detection method of the secondary battery 100 has been described taking as an example the case where the secondary battery 100 constituting the assembled battery 10 is charged. However, the state detection method of the third embodiment can be applied also at the time of discharge of the secondary battery 100 by changing a part of the routine shown in FIGS. 17 and 18.

Specifically, after the discharge of the secondary battery 100 is started in step S1 of the main routine shown in FIG. 17, the processes of steps S2 to S6 are performed similarly to the third embodiment. Subsequently, the procedure proceeds to step T7, in which the processes of steps T73 and T74 are performed first, and then the processes of steps T71 and T72 are performed. Thereafter, similarly to the third embodiment, by performing the processing of steps T75 to T7B, the drop or abnormality (internal short circuit) of the battery capacity of the secondary battery 100 can be detected appropriately.

In addition, also in the fourth embodiment, the state detection method of the secondary battery 100 has been described with an example of charging the secondary battery 100 constituting the assembled battery 10. However, the state detection method of the fourth embodiment can be applied also at the time of discharge of the secondary battery 100 by changing a part of the routine shown in FIGS. 23 and 24.

Specifically, after the discharge of the secondary battery 100 is started in step S1 of the main routine shown in FIG. 23, the processes of steps S2 to S6 are performed similarly to the fourth embodiment. Subsequently, the procedure proceeds to step U7, in which the processing of steps U73 and U74 is performed first, and then the processing of steps U71 and U72 is performed. Thereafter, similarly to the fourth embodiment, by performing the processing of steps U75 to U7B, an increase in the internal resistance of the secondary battery 100 and a poor connection can be detected appropriately.

6, 16, 26, 36: secondary battery system
10: battery pack
30, 130, 230: Battery controller (dV / dQ calculation means, power storage amount estimating means, power storage amount correcting means, deterioration detecting means, capacity drop detecting means, resistance rise detecting means, abnormality detecting means, non-short detection means, poor connection Detection means)
40: voltage detection means
50: current detection means
100: secondary battery
120: positive electrode terminal
130: negative electrode terminal
150: electrode body
153: positive electrode active material (second active material)
154: negative electrode active material (first active material)
155: positive electrode plate (second electrode plate)
156: negative electrode plate (first electrode plate)
157: Separator

Claims (11)

A secondary battery system having a secondary battery,
The secondary battery includes an electrode body having a first electrode plate, a second electrode plate, and a separator,
The first electrode plate includes a first active material accompanying a phase change by charging and discharging,
The said 2nd electrode plate contains the 2nd active material which charges / discharges of 2-phase coexistence type,
The secondary battery system,
At the time of charging and discharging of the secondary battery, the battery voltage V of the secondary battery with respect to the change amount dQ of the electrical storage amount Q when the electrical storage amount Q of the secondary battery is changed. And dV / dQ calculating means for calculating a value of dV / dQ which is a ratio of the change amount dV,
Characteristic points appearing on a Q-dV / dQ curve representing the relationship between the value of the electric storage amount Q and the value of dV / dQ, or the relationship between the value of the battery voltage V and the value of dV / dQ. The state of the secondary battery system is detected using the feature points appearing on the V-dV / dQ curve,
The second active material is LiFe _(1-X) M _X PO ₄ (M is at least any one of Mn, Cr, Co, Cu, Ni, V, Mo, Ti, Zn, Al, Ga, Mg, B, Nb) One, 0≤X≤0.5),
The secondary battery system, wherein the first active material is a carbon material. The method of claim 1, wherein the secondary battery system,
Based on the value of dV / dQ, whether the secondary battery has reached a state corresponding to a feature point on the Q-dV / dQ curve, and the secondary battery corresponds to a feature point on the V-dV / dQ curve. Determine at least one of whether a state has been reached,
A value of the power storage amount Q at a feature point on the Q-dV / dQ curve, and a power storage amount Q at two specific feature points selected from a plurality of feature points present on the Q-dV / dQ curve. The state of the secondary battery system is detected based on the difference value of the battery voltage (V) at two specific points selected from a plurality of feature points present on the V-dV / dQ curve Secondary battery system. delete delete The power storage amount estimation means for estimating the power storage amount Q of the secondary battery,
Judging means for judging whether or not the secondary battery has reached a state corresponding to a feature point indicated on the Q-dV / dQ curve based on the value of dV / dQ;
Power storage amount correction means for correcting the estimated power storage amount Q,
The power storage correction means,
The electrical storage when the secondary battery has reached the state corresponding to the characteristic point by the determining means from the characteristic reference value which is the value of the electrical storage amount Q at the characteristic point stored in the secondary battery system in advance; The secondary battery system corrects the estimated power storage amount (Q) by a difference value obtained by subtracting a feature estimation value that is a value of the power storage amount (Q) of the secondary battery estimated by the amount estimation means. The method of claim 1, further comprising: deterioration detecting means for detecting deterioration of the secondary battery;
Based on the value of dV / dQ, whether the secondary battery has reached a state corresponding to the feature point indicated on the Q-dV / dQ curve and whether the secondary battery appears on the V-dV / dQ curve Determination means for judging at least one of whether a state corresponding to the feature point has been reached,
The deterioration detection means,
The difference value of the electrical storage quantity Q in two specific feature points selected from a plurality of feature points present on the Q-dV / dQ curve determined by the judging means is smaller than the preset reference difference value. In the case, or the difference value of the battery voltage V at two specific feature points selected from a plurality of feature points present on the V-dV / dQ curve determined by the judging means is a preset reference. The secondary battery system which judges that the said secondary battery has deteriorated when it is larger than a difference value. The method of claim 6, wherein the secondary battery system,
Determination means for determining whether or not the secondary battery has reached a state corresponding to a feature point appearing on the Q-dV / dQ curve based on the value of dV / dQ;
The deterioration detection means,
A capacity decrease detection means for detecting a decrease in battery capacity of the secondary battery;
The capacity drop detection means,
It is the said reference differential value which is the difference value of the said electrical storage quantity Q in the said two characteristic points on the said Q-dV / dQ curve previously memorize | stored in the said secondary battery system, and relates to the said secondary battery of an initial state. The measured difference value is compared with the measured difference value which is the difference value between the reference difference value and the power storage amount Q at the two feature points on the Q-dV / dQ curve determined by the determination means. The secondary battery system which judges that the battery capacity of the said secondary battery is falling when it is smaller than the said reference difference value. The method of claim 6 or 7, wherein the secondary battery system,
Determination means for determining whether or not the secondary battery has reached a state corresponding to a feature point appearing on the V-dV / dQ curve based on the value of dV / dQ;
The deterioration detection means,
Resistance increase detection means for detecting an increase in internal resistance of the secondary battery;
The resistance rise detection means,
It is a reference difference value which is a difference value of the said battery voltage (V) in the said two characteristic points on the said V-dV / dQ curve previously memorize | stored in the said secondary battery system, The said about the said secondary battery of an initial state The measured difference value is compared with a reference difference value and an actual difference value that is a difference value of the battery voltages V at the two feature points on the V-dV / dQ curve determined by the determination means. The secondary battery system judges that the internal resistance of the said secondary battery is rising when it is larger than a reference difference value. The method of claim 1, further comprising: abnormality detecting means for detecting an abnormality of the secondary battery system;
Based on the value of dV / dQ, whether the secondary battery has reached a state corresponding to the feature point indicated on the Q-dV / dQ curve and whether the secondary battery appears on the V-dV / dQ curve Determination means for judging at least one of whether a state corresponding to the feature point has been reached,
The abnormality detection means,
The difference value of the electrical storage quantity Q in two specific feature points selected from a plurality of feature points present on the Q-dV / dQ curve determined by the judging means is smaller than the preset reference difference value. The difference of the battery voltage V at two specific points selected from a plurality of feature points present on the V-dV / dQ curve or smaller than a predetermined threshold value or determined by the determination means. The secondary battery system which judges that the said secondary battery system is abnormal, when a value is larger than predetermined reference difference value and larger than a predetermined threshold value. The method of claim 9, wherein the secondary battery system,
Determination means for determining whether or not the secondary battery has reached a state corresponding to a feature point appearing on the Q-dV / dQ curve based on the value of dV / dQ;
The abnormality detection means,
Non-short detection means for detecting a short-circuit of the secondary battery,
The non-short detection means,
It is the said reference differential value which is the difference value of the said electrical storage quantity Q in the said two characteristic points on the said Q-dV / dQ curve previously memorize | stored in the said secondary battery system, and relates to the said secondary battery of an initial state. The measured difference value is compared with the measured difference value which is the difference value between the reference difference value and the power storage amount Q at the two feature points on the Q-dV / dQ curve determined by the determination means. And a secondary battery system for determining that a short circuit has occurred in the secondary battery when smaller than the reference difference value and smaller than a predetermined threshold value. The method of claim 9 or 10, wherein the secondary battery system,
Determination means for determining whether or not the secondary battery has reached a state corresponding to a feature point appearing on the V-dV / dQ curve based on the value of dV / dQ;
The abnormality detection means,
A connection failure detection means for detecting a connection failure of the secondary battery,
The connection failure detection means,
It is a reference difference value which is a difference value of the said battery voltage (V) in the said two characteristic points on the said V-dV / dQ curve previously memorize | stored in the said secondary battery system, The said about the said secondary battery of an initial state The measured difference value is compared with a reference difference value and an actual difference value that is a difference value of the battery voltages V at the two feature points on the V-dV / dQ curve determined by the determination means. The secondary battery system which judges that the connection fault of the said secondary battery has generate | occur | produced when it is larger than the said reference difference value and larger than a predetermined threshold value.

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